Probiotics and performance

Probiotic bacteria are live organisms which occur naturally in fermented food products such as milk, yoghurt, cabbage and soy bean-based miso. However, foods such as yoghurt and milk are the best option for probiotic intake due to the live microorganism content.

There is a growing body of evidence to show probiotics may help maintain or boost immune function in athletes or individuals who engage in regular strenuous activity. Athletes are susceptible to an increase in upper respiratory tract infection (URTI) and as such, any intervention to help reduce this risk to performance, is certainly a keen area of interest.

Whilst it remains unclear as to what the exact cause of the increase in URTI observed in athletic populations, popular theories include increased physical stress, increased psychological stress, inadequate diet, disturbed sleep, exposure to environmental extremes or a combination of stressors. Research has focussed on a number of different areas with differing findings.

Upper respiratory tract infections

Various probiotic strains have been found to reduce the severity of symptoms related to URTI and the duration of symptoms. However, the incidents of URTI did not decline.

Respiratory and gastrointestinal symptoms in endurance athletes

A study involving competitive cyclists found that 11 weeks of supplementing with Lactobacillus probiotic (the same probiotic found in Yakult), reduced the severity of gastrointestinal illnesses and the severity and duration of respiratory illnesses was also reduced. Unfortunately, no performance measures were recorded.

Traveller’s diarrhoea

Many athletes have to travel for training and competition, which can cause significant disruption to an athletes diet, training and health. Traveller’s diarrhoea develops during, or shortly after, you have travelled abroad. It is caused by eating food, or drinking water, containing certain germs or toxins.

Four weeks of probiotic supplementation prior to travel has been demonstrated to be effective in preventing traveller’s diarrhoea. Various strains of probiotic have been researched and have been found to hamper the growth of diarrhoeal pathogens and boosting immunity.

Conclusion

The British Association of Sport and Exercise Sciences Expert Statement states that there is evidence that Lactobacillus probiotics can reduce URTI incidence and daily supplementation could reduce the risk of gastrointestinal infections in highly active individuals.

Lactobacillus and bifidobacterium strains can limit impact of traveller’s darrhoea.

There are currently no recommended dosage guidelines, though most studies report effective dosages of 1-10 billion bacteria per day.